Optoelectronic device manufacturing method

ABSTRACT

A method of manufacturing an optoelectronic device, including the steps of: a) arranging an active photosensitive diode stack on a first substrate; b) transferring the active photosensitive diode stack onto an integrated control circuit previously formed inside and on top of a second semiconductor substrate, and then removing the first substrate; c) arranging an active light-emitting diode stack on a third substrate; and d) after steps b) and c), transferring the active light-emitting diode stack onto the active photosensitive diode stack, and then removing the third substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to French application number 2111479,filed Oct. 28, 2021 and French application number 2105160, filed May 18,2021, the contents of which are incorporated by reference in itsentirety.

TECHNICAL BACKGROUND

The present disclosure generally concerns the field of optoelectronicdevices, and more particularly aims at a method of manufacturing anoptoelectronic device combining a light emission function and an opticalcapture function.

PRIOR ART

Various applications are likely to benefit from an optoelectronic devicecombining a light emission function and an optical capture function.Such a device may for example be used to form an interactive displayscreen.

SUMMARY OF THE INVENTION

An object of an embodiment is to overcome all or part of thedisadvantages of known solutions for forming an optoelectronic devicecombining a light emission function and an optical capture function.

An embodiment provides an optoelectronic device manufacturing method,comprising the steps of:

a) arranging an active photosensitive diode stack on a first substrate;

b) transferring the active photosensitive diode stack onto an integratedcontrol circuit previously formed inside and on top of a secondsemiconductor substrate, and then removing the first substrate;

c) arranging an active light-emitting diode stack on a third substrate;and

d) after steps b) and c), transferring the active light-emitting diodestack onto the active photosensitive diode stack, and then removing thethird substrate.

According to an embodiment, the active photosensitive diode stackcomprises at least one inorganic semiconductor layer, for example, madeof a III-V material, and the active light-emitting diode stack comprisesat least one inorganic semiconductor layer, for example, made of a III-Vmaterial.

According to an embodiment, the active photosensitive diode stackcomprises first, second, and third semiconductor layers, the secondlayer being arranged between the first and third layers.

According to an embodiment, the method comprises a step of P-type dopingof local portions of the first layer, said portions defining anoderegions of photosensitive diodes of the device.

According to an embodiment, the step of P-type doping of the localportions of the first layer is implemented after step b) and before stepd).

According to an embodiment, the step of P-type doping of the localportions of the first layer is implemented before step b).

According to an embodiment, the method further comprises a step offorming of connection metallizations on top of and in contact with saidlocal portions of the first layer.

According to an embodiment, at the end of step b), the activephotosensitive diode stack continuously extends over the entire surfaceof the integrated control circuit.

According to an embodiment, at the end of step d), the activelight-emitting diode stack continuously extends over the entire surfaceof the integrated control circuit.

According to an embodiment, the method further comprises, after step b)and before step d), a step of forming of conductive vias crossing theactive photosensitive diode stack.

According to an embodiment, the conductive vias are electricallyconnected to metal connection pads of the integrated circuit.

According to an embodiment, the method further comprises, after step d),a step of local etching of the active light-emitting diode stack to formin the active light-emitting diode stack a plurality of tiles, eachdefining a light-emitting diode.

According to an embodiment, the method comprises the forming of colorconversion elements above at least some of the light-emitting diodes.

According to an embodiment, at least one of the light-emitting diodes istopped with a photoluminescent conversion element adapted to convertingthe light emitted by the light-emitting diode into a visible wavelengthand at least another one of the light-emitting diodes is topped with aphotoluminescent conversion element adapted to converting the lightemitted by the light-emitting diode into a light radiation in thewavelength range of sensitivity of the active photosensitive diodestack, preferably an infrared radiation.

According to an embodiment, at least one of the light-emitting diodes isnot topped with a photoluminescent conversion element.

According to an embodiment, the photoluminescent conversion elements areformed based on quantum dots or on perovskite materials.

According to an embodiment, the method comprises, after step d), a stepof bonding of a temporary support substrate on the side of the activelight-emitting diode stack opposite to the integrated circuit, followedby a step of cutting of the assembly comprising the integrated circuit,the active photosensitive diode stack, and the active light-emittingdiode stack into a plurality of elementary chips.

According to an embodiment, the method further comprises a step oftransfer and of bonding of the elementary chips onto a transfersubstrate of the device, followed by a step of removal of the temporarysupport substrate.

Another embodiment provides an optoelectronic device comprising atransfer substrate and a plurality of elementary chips bonded andelectrically connected to the transfer substrate, each elementary chipcomprising a stack comprising, in the order from the upper surface ofthe transfer substrate, an integrated control circuit formed inside andon top of a semiconductor substrate, a photodetection stage comprisingat least one photosensitive diode, and an emission stage comprising atleast one light-emitting diode.

According to an embodiment, in each elementary chip, the photodetectionstage is arranged between the integrated control circuit and theemission stage, and the photosensitive diode has a semiconductor anodelayer arranged on the side of the emission stage and a semiconductorcathode layer arranged on the side of the integrated control circuit.

Another embodiment provides a system comprising an optoelectronic deviceformed by a method such as defined hereabove, and a light source adaptedto emitting a light radiation in the wavelength range of sensitivity ofthe active photosensitive diode stack, preferably an infrared radiation.

According to an embodiment, the light source is a remote source.

According to an embodiment, the light source is integrated to theoptoelectronic device and comprises at least one light-emitting diodeformed in the active light-emitting diode stack.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing features and advantages, as well as others, will bedescribed in detail in the following description of specific embodimentsgiven by way of illustration and not limitation with reference to theaccompanying drawings, in which:

FIGS. 1A, 1B, 1C, 1D, 1E, 1F, 1G, 1H, 1I, and 1J are cross-section viewsillustrating successive steps of an embodiment of an optoelectronicdevice manufacturing method according to an embodiment;

FIGS. 2A, 2B, 2C, 2D, 2E, 2F, and 2G are cross-section viewsillustrating other successive steps of an example of a method ofmanufacturing an optoelectronic device according to an embodiment;

FIG. 3 schematically shows an example of a system comprising anoptoelectronic device according to an embodiment;

FIG. 4 is a cross-section view partially and schematically illustratinganother example of an optoelectronic device according to an embodiment;and

FIG. 5 is a cross-section view schematically and partially illustratingan alternative embodiment of the device of FIG. 4.

DESCRIPTION OF THE EMBODIMENTS

Like features have been designated by like references in the variousfigures. In particular, the structural and/or functional features thatare common among the various embodiments may have the same referencesand may dispose identical structural, dimensional and materialproperties.

For the sake of clarity, only the steps and elements that are useful foran understanding of the embodiments described herein have beenillustrated and described in detail. In particular, the forming of thephotosensitive diodes, of the light-emitting diodes (LED), and of theintegrated control circuits of the described devices has not beendetailed, the detailed implementation of these elements being within theabilities of those skilled in the art based on the functionalindications of the present description. Further, the variousapplications that the described embodiments may have have not beendetailed, the described embodiments being compatible with all or most ofthe applications likely to benefit from a device combining a lightemission function and an optical capture function (photodetection).

Unless indicated otherwise, when reference is made to two elementsconnected together, this signifies a direct connection without anyintermediate elements other than conductors, and when reference is madeto two elements coupled together, this signifies that these two elementscan be connected or they can be coupled via one or more other elements.

In the following description, when reference is made to terms qualifyingabsolute positions, such as terms “front”, “back”, “top”, “bottom”,“left”, “right”, etc., or relative positions, such as terms “above”,“under”, “upper”, “lower”, etc., or to terms qualifying directions, suchas terms “horizontal”, “vertical”, etc., it is referred unless specifiedotherwise to the orientation of the drawings.

Unless specified otherwise, the expressions “around”, “approximately”,“substantially” and “in the order of” signify within 10%, and preferablywithin 5%.

According to an aspect of an embodiment, it is provided, to form anoptoelectronic device combining a light emission function and aphotodetection function, to implement the following steps:

a) arranging an active photosensitive diode stack on a first substrate;

b) transferring the active photosensitive diode stack onto an integratedcontrol circuit previously formed inside and on top of a secondsemiconductor substrate, and then removing the first substrate;

c) arranging an active LED stack on a third substrate; and

d) after steps b) and c), transferring the active LED stack onto theactive photosensitive diode stack, and then removing the thirdsubstrate.

FIGS. 1A to 1J are cross-section views illustrating successive steps ofa non-limiting example of implementation of such a method. Differentvariants are within the abilities of those skilled in the art based onthe indications of the present description.

FIG. 1A schematically illustrates, in its upper portion (A), thestructure obtained at the end of steps of forming of an activephotosensitive diode stack 103 on the upper surface of a substrate 101.

Stack 103 preferably is a stack of inorganic semiconductor layers. Stack103 for example comprises one or a plurality of layers made of aIII-V-type semiconductor material. Stack 103 is for example an activephotodiode stack sensitive in infrared or near infrared. As a variant,stack 103 is an active photodiode stack sensitive in the visible range.As an example, stack 103 comprises, in the order from the upper surfaceof substrate 101, a layer 103 a of non-intentionally doped indiumphosphide (InP), an absorption layer 103 b of indium-gallium arsenide(InGaAs), for example, intrinsic or lightly N-type doped (for example,in the order of 10 ¹⁵ atoms/cm³), and a layer 103 c of N-type dopedindium phosphide (InP). As an example, the N-type doping level of layer103 c is in the range from 10 ¹⁶ to 10 ¹⁸ atoms/cm³. In this example,layer 103 b is in contact, by its lower surface, with the upper surfaceof layer 103 a, and layer 103 c is in contact, by its lower surface,with the upper surface of layer 103 b.

Substrate 101 is for example made of indium phosphide. Layers 103 a, 103b, and 103 c may be successively formed by epitaxy on the upper surfaceof substrate 101. Substrate 101 then is a growth substrate. A bufferlayer, not shown, for example, made of indium phosphide, may possiblyform an interface between substrate 101 and layer 103 a. Buffer layer isfor example in contact, by its lower surface, with the upper surface ofsubstrate 101, and by its upper surface, with the lower surface of layer103 a. The buffer layer may also be formed by epitaxy from the uppersurface of substrate 101, before the forming of layers 103 a, 103 b, and103 c.

As a variant, rather than forming active photosensitive diode stack 103by epitaxy on the upper surface of substrate 101, the active stack maybe formed in the inverse order on a growth substrate, not shown, andthen transferred and bonded onto substrate 101. In this case, layers 103c, 103 b, and 103 a are successively formed by epitaxy on a surface ofthe growth substrate. A buffer layer, for example, of indium phosphide,may possibly form an interface between the growth substrate and layer103 c. Stack 103 is then bonded to the upper surface of substrate 101,for example, by direct bonding or molecular bonding of the lower surfaceof layer 103 a to the upper surface of substrate 101. As a variant,other bonding methods may be used. The growth substrate and, possibly,the buffer layer forming an interface between the growth substrate andlayer 103 c, are then removed to clear the access to the upper surfaceof layer 103 c. In this variant, substrate 101 is a support substrate,for example, made of silicon, or of any other material adapted to beingused as a support for receiving active stack 103.

FIG. 1A further illustrates, in its upper portion (A), a step ofdeposition of a dielectric layer 105, for example, made of silicon oxideor of silicon nitride, on top of and in contact with the upper surfaceof the upper layer 103 c of active photosensitive diode stack 103. Inthis example, dielectric layer 105 extends continuously and with asubstantially uniform thickness over the entire upper surface of layer103 c.

FIG. 1A further schematically illustrates, in its intermediate portion(B), the structure obtained at the end of steps of forming of an activeLED stack 113 on the upper surface of a substrate 111.

Stack 113 preferably is a stack of inorganic semiconductor layers. Stack113 for example comprises one or a plurality of layers made of aIII-V-type semiconductor material. Stack 113 is for example an activeLED stack adapted to emitting visible light, for example, mainly bluelight. As an example, stack 113 is an active gallium nitride (GaN) LEDstack. As an example, stack 113 comprises, in the order from the uppersurface of substrate 111, an N-type doped semiconductor layer 113 a,forming a cathode layer of the LED stack, an active layer 113 b, and aP-type doped semiconductor layer 113 c, forming an anode layer of theLED stack. Layer 113 a is for example made of gallium nitride. Activelayer 113 b is for example a multiple quantum well stack (not detailedin the drawing), formed of an alternation of semiconductor layers of afirst material, for example, a III-V-type material, and of semiconductorlayers of a second material, for example, a III-V-type material, eachlayer of the first material being sandwiched between two layers of thesecond material and defining a quantum well. Layer 113 c is for examplemade of gallium nitride. Active layer 113 b is for example in contact,by its lower surface, with the upper surface of layer 113 a. Layer 113 cis for example in contact, by its lower surface, with the upper surfaceof active layer 113 b.

Substrate 111 is for example made of silicon, of sapphire, or of galliumnitride. As an example, layers 113 a, 113 b, and 113 c are successivelyformed by epitaxy on the upper surface of substrate 111. A buffer layer,not shown, may possibly form an interface between the upper surface ofsubstrate 111 and the lower surface of layer 113 a.

At this stage, each of the layers of active photosensitive diode stack103 extends, for example, continuously and with a substantially uniformthickness over the entire upper surface of substrate 101. Further, eachof the layers of active LED stack 113 for example extends substantiallycontinuously and with a substantially uniform thickness over the entireupper surface of substrate 111. Substrates 101 and 111 for example havesubstantially the same lateral dimensions.

FIG. 1A further illustrates, in its intermediate portion (B), a step ofdeposition of a conductive layer 115 on top of and in contact with theupper surface of semiconductor layer 113 c. Layer 115 forms an ohmiccontact with the semiconductor material of layer 113 c. Layer 115 is forexample made of aluminum, of nickel, or also of a transparent conductiveoxide, for example, of indium-tin oxide (ITO). At this stage, metallayer 115 extends continuously and with a substantially uniformthickness over the entire upper surface of layer 113 c. Layer 115 mayfurther have an optical reflector function. As an example, layer 115 maycomprise two stacked layers respectively ensuring the function of ohmiccontact with the semiconductor material of layer 113 c and the opticalreflector function.

FIG. 1A further schematically illustrates, in its lower portion (C), anintegrated control circuit 151 previously formed inside and on top of asemiconductor substrate, for example, made of silicon. Integratedcontrol circuit 151 comprises circuits for controlling and reading theLEDs and the photosensitive diodes of the device. As an example,integrated circuit 151 comprises an assembly of elementary control andreadout cells, enabling to individually control and read each LED andeach photosensitive diode of the device. Integrated circuit 151 is forexample a CMOS (“Complementary Metal Oxide Semiconductor”) circuit. Inthis example, circuit 151 comprises a plurality of metal connection pads153 arranged on its upper surface side.

FIG. 1A further illustrates, in its upper portion (C), a step ofdeposition of a dielectric layer 107, for example, made of silicon oxideor of silicon nitride, for example, made of the same material as layer105, on top of and in contact with the upper surface of integratedcontrol circuit 151. In this example, dielectric layer 107 extendscontinuously and with a substantially uniform thickness over the entireupper surface of integrated control circuit 151.

FIG. 1B illustrates the structure obtained at the end of a step oftransfer and of bonding of active photosensitive diode stack 103 ontointegrated control circuit 151, and then of removal of substrate 101.During this step, active photosensitive diode stack 103 is transferredonto integrated circuit 151, by using substrate 101 as a support handle.In FIG. 1B, the structure comprising substrate 101 and stack 103 isflipped with respect to the orientation of FIG. 1A. Stack 103 is thenbonded to integrated circuit 151. In this example, stack 103 is bondedby direct bonding or molecular bonding of the lower surface (in theorientation of FIG. 1B, corresponding to the upper surface in theorientation of FIG. 1A) of layer 105 onto the upper surface (in theorientation of FIG. 1B, corresponding to the upper surface in theorientation of FIG. 1A) of layer 107. As a variant, other bondingmethods may be used. Substrate 101 is then removed, for example, bygrinding and/or chemical etching, to clear the access to the uppersurface of layer 103 a. At this stage, each of the layers of activephotosensitive diode stack 103 extends for example continuously and witha substantially uniform thickness over the entire surface of integratedcontrol circuit 151. It should be noted that, in this example, activestack 103 is non-structured and has been submitted to no step of localtreatment before the transfer step. Thus, the transfer step requires nospecific alignment.

FIG. 1C illustrates a step of deposition of a dielectric layer 121, forexample, made of silicon nitride or of silicon oxide, on the uppersurface of layer 103 a, for example, in contact with the upper surfaceof layer 103 a. Layer 121 is for example deposited by a plasma-enhancedchemical vapor deposition (PECVD) method. Layer 121 is for examplecontinuously deposited with a uniform thickness over the entire uppersurface of layer 103 a. FIG. 1C further illustrates a step of forming oflocal through openings 123 in dielectric layer 121. Openings 123 are forexample formed by photolithography and etching. The openings arearranged opposite future P-type contacting areas corresponding to anoderegions of the photosensitive diodes of the device.

FIG. 1D illustrates a step of P-type doping of local regions 125 oflayer 103 a, located opposite openings 123. The doping of regions 125may be performed by diffusion or implantation of P-type dopant elements,for example, zinc (Zn) or beryllium (Be), opposite openings 123. Ananneal of activation of the dopant elements may then be implemented. Asan example, the activation anneal may be a surface laser anneal, whichenables not to damage integrated circuit components 151, nor to alterthe quality of the bonding between integrated circuit 151 and activephotosensitive diode stack 103. P-type doped regions 125 form anoderegions of the photosensitive diodes of the device. In this example,regions 125 extend across the entire thickness of layer 103 a, and comeinto contact, by their lower surface, with the upper surface ofabsorption layer 103 b.

FIG. 1E illustrates a step of forming of contacting metallizations 127in openings 123. Each metallization 127 individually contacts theunderlying region 125, through the corresponding opening 123. As anexample, a metal layer is first continuously deposited over the entireupper surface of the structure, that is, on top of and in contact withthe upper surface of dielectric layer 121 and in openings 123, and thenremoved by photolithography and etching to only keep metallizations 127.In this example, each metallization 127 forms an anode electrode of aphotosensitive diode 171 of the device.

FIG. 1F illustrates the structure obtained at the end of steps offorming of laterally-insulated conductive vias 129, crossing activephotosensitive diode stack 103. More particularly, in this example,conductive vias 129 cross layer 121, layers 103 a, 103 b, and 103 c ofstack 103, insulating layers 105 and 107, and each emerge onto and incontact with the upper surface of a metal pad 153 of the integratedcontrol circuit. The forming of vias 129 comprises a step of etching,from the upper surface of insulating layer 121, of through openings inthe stack formed by layers 107, 105, 103 c, 103 b, 103 a, and 121. Theopenings are for example formed by plasma etching, for example of ICP(Inductively Coupled Plasma) type. A step of passivation of the sides ofthe openings is then implemented. During this step, a layer 131 of aninsulating material, for example, silicon oxide, is deposited on thelateral walls and at the bottom of the openings. A step of verticalanisotropic etching may then be implemented to remove the insulatinglayer from the bottom of the openings, without removing it from thelateral walls. The openings are then filled with metal to formconductive vias 129.

Before or after the forming of conductive vias 129, one or a pluralityof contacting conductive vias (not shown in the drawings) on the cathodelayer 103 c of the photosensitive diode stack may be formed. Thesecathode contacting vias are similar to the vias 129 shown in FIG. 1F,that is, they cross layer 121, the layers 103 a, 103 b, and 103 c ofstack 103, insulating layers 105 and 107, and emerge onto and in contactwith the upper surface of a metal pad 153. The cathode contacting viasdiffer from vias 129 in that they are in contact, laterally, with thesides of the semiconductor cathode layer 103 c of the photosensitivediode stack. The cathode contacting vias are however laterally insulatedfrom anode semiconductor layer 103 a by a lateral insulation layer. Toform the lateral insulation layer which coats the sides of anodesemiconductor layer 103 a and does not coat the sides of cathodesemiconductor layer 103 a, a possibility is to deposit the insulatingpassivation material by sputtering, with angle of incidence, so that theinsulating material only deposits on an upper portion of the walls ofthe opening of the via. The deposition depth may be adjusted by varyingthe applied inclination angle. As a variant, the cathode contacting viasmay be formed in two successive etch steps. During a first etch step, afirst opening crossing anode semiconductor layer 103 a and all or partof absorption layer 103 b is formed. An insulating passivation layer isthen deposited on the lateral walls of the first opening. During asecond etch step, a second opening crossing cathode semiconductor layer103 c is formed, the second opening having lateral dimensions smallerthan those of the first opening. The first and second openings are thenfilled with metal.

FIG. 1G illustrates the structure obtained at the end of a step ofdeposition of a metal layer 143 on the upper surface of the structure ofFIG. 1F. In this example, metal layer 143 extends continuously with asubstantially uniform thickness over the entire upper surface of thestructure of FIG. 1F. In the shown example, prior to the deposition ofmetal layer 143, a step of planarization of the upper surface of thestructure is implemented, for example, by a damascene-type method. Forthis purpose, an insulating layer 141, for example, made of siliconoxide, is deposited over the entire upper surface of the structure ofFIG. 1F, across a thickness greater than the thickness of the portionsof metallizations 127 and 129 protruding from the upper surface ofinsulating layer 121. Insulating layer 141 is then planarized from itsupper surface, for example, by chemical-mechanical polishing, to clearthe access to the upper surface of metallizations 127 and 129. A planarupper surface exhibiting an alternation of insulating and metal regionsis thus obtained. Metal layer 143 is then deposition on top of and incontact with this planarized surface. Metal layer 143 is for examplemade of the same metal as the metal layer 115 deposited on the uppersurface of LED stack 113 (FIG. 1A).

FIG. 1H illustrates the structure obtained at the end of a step oftransfer and bonding of active LED stack 113 onto the upper surface ofthe structure of FIG. 1G, and then of removal of substrate 111. Duringthis step, active LED stack 113 is transferred onto the upper surface ofthe structure of FIG. 1G, by using substrate 111 as a support handle. InFIG. 1H, the structure comprising substrate 111, stack 113, and layer115 is turned upside down with respect to the orientation of FIG. 1A.Stack 113 is then bonded to the structure of FIG. 1G. As an example,stack 113 is bonded by direct bonding or molecular bonding of the lowersurface (in the orientation of FIG. 1H, corresponding to the uppersurface in the orientation of FIG. 1A) of layer 115 onto the uppersurface (in the orientation of FIG. 1H, corresponding to the uppersurface in the orientation of FIG. 1G), of the upper metal layer 143 ofthe structure of FIG. 1G. Preferably, the bonding is a bonding of SAB(“Surface Activated Bonding”) type, that is, a direct bonding where thesurfaces placed into contact are previously activated by atombombarding. The SAB bonding has the advantage of being capable of beingimplemented at low temperature, for example, at room temperature.Substrate 111 is then removed, for example, by grinding and/or chemicaletching, or by a laser separation method, to clear the access to theupper surface of layer 113 a. At this stage, each of the layers ofactive LED stack 113 for example extends continuously and with asubstantially uniform thickness, over the entire surface of the activestack of the assembly. It should be noted that in this example, activeLED stack 113 is non-structured and has been submitted to no localtreatment step before the transfer step. Thus, the transfer steprequires no specific alignment.

FIG. 1I illustrates the structure obtained at the end of a step offorming of cathode contact metallizations 145 of the LEDs of the devicein openings crossing active LED stack 113 and metal layers 115 and 143.Each cathode contact metallization 145 extends vertically from the uppersurface of the stack all the way to the upper surface of a conductivevia 129 of the device. Thus, each cathode contact metallization 145 iselectrically connected, via the underlying conductive via 129, to adedicated metal connection pad 153 of integrated control circuit 151.

A step of local etching of layers 113 a, 113 b, 113 c, 115, and 143 isfirst implemented to form the openings intended to receivemetallizations 145. A step of passivation of the opening sides is thenimplemented. During this step, a layer 147 of an insulating material,for example, silicon oxide, is deposited on the lateral walls and at thebottom of the openings. A step of vertical anisotropic etching may thenbe implemented to remove insulating layer 147 from the bottom of theopenings. Insulating layer 147 may further be removed, inside of theopenings, from the sides of an upper portion of the cathode layer 113 aof LED stack 113. Insulating layer 147 is however kept, inside of theopenings, on the sides of layers 113 b, 113 c, 115, and 143. Theopenings are then filled with metal to form metallizations 145. Thus,each metallization 145 is in contact with the N-type layer 113 a of theactive LED stack at the level of the lateral walls of the opening. Eachmetallization 145 is however laterally insulated from layers 113 b, 113c, 115, and 143 by insulating layer 147.

FIG. 1J illustrates the structure obtained at the end of a step of localetching of the stack formed by metal layers 143 and 115 and active LEDstack 113. During this step, only are kept tiles 161 of active LED stack113, respectively corresponding to the different LEDs 161 of the device.In this example, each LED tile 161 comprises a cathode contactmetallization 145. The portion of the stack of metal layers 115 and 143located under each LED 161 forms an anode electrode of the LED and iselectrically connected to a dedicated pad 153 of integrated circuit 151via a via 129.

Outside of LED tiles 161, stack 113 and metal layers 115 and 143 areentirely removed, to expose the upper surface of dielectric layer 141and of the underlying metallizations 129 and 127. In particular, in thisexample, stack 113 and layers 115 and 143 are removed opposite thephotosensitive diodes 171 of the device.

A subsequent step of passivation of the sides of LEDs 161, not detailed,may optionally be provided.

It should be noted that in the shown example, the anode electrodes 127of photosensitive diodes 171 and the anode electrodes 115, 143 and thecathode electrodes 145 of LEDs 161 are all individually connected toconnection pads 153 of integrated circuit 151. The cathode electrode(s)of photosensitive diodes 171 may be common to all the photosensitivediodes 171 of the device, and connected to integrated circuit 151 at theperiphery of the device, via cathode contacting vias of theabove-described type.

As a variant, the cathode electrodes of LEDs 161 may be common to allthe LEDs 161 of the device, and connected to integrated circuit 151 atthe periphery of the device, to limit the number of conductive vias 129and of pads 153. In another variant, not shown, the cathode electrodesof LEDs 161 and of photosensitive diodes 171 may be common.

According to the envisaged application, light conversion elements, notshown, may possibly be arranged opposite LEDs 161, on their uppersurface sides, to obtain, on a same device, emission pixels adapted toemitting in different wavelength ranges, for example, red pixels, greenpixels, and blue pixels. Further, filtering elements, not shown, may bepossibly arranged opposite photosensitive diodes 171, on their uppersurface sides, to obtain, on a same device, detection pixels adapted todetecting radiations in different wavelength ranges.

The method described in relation with FIGS. 1A to 1J may be used to formmonolithic microdisplays, combining an image display function and anoptical capture function, for example, to form an interactive displayscreen adapted to implementing functions of face or shape recognition,of motion detection, of identification, etc. An advantage of thedescribed method is that it enables to form display pixels and capturepixels of small lateral dimensions, and thus obtain high displayresolutions and capture resolutions. It should be noted that in theabove-described example, each pixel of the device comprises aphotosensitive diode 171 and a LED 161. As a variant, the resolution ofthe display device and the resolution of the optical sensor may bedifferent. For example, the number of photosensitive diodes 171 of thedevice may be smaller than the number of LEDs 161.

As a variant, the method described in relation with FIGS. 1A to 1J maybe used to form interactive display devices of larger dimensions, forexample, a screen for a television, computer, smartphone, digitaltablet, etc. Such a device may comprise a plurality of elementaryelectronic chips arranged, for example, according to an array layout, ona same transfer substrate. The elementary chips are rigidly assembled tothe transfer substrate and connected to electric connection elements ofthe transfer substrate for their control. Each chip comprises one or aplurality of LEDs 161, one or a plurality of photosensitive diodes 171,and a circuit 151 for controlling said one or a plurality of LEDs andsaid one or a plurality of photosensitive diodes. Each chip for examplecorresponds to a pixel of the device. As an example, each chip comprisesthree individually-controllable LEDs 161 respectively defining threesub-pixels adapted to respectively emitting red light, green light, andblue light, and a photosensitive diode 171 adapted to detecting aninfrared or near-infrared radiation.

FIGS. 2A to 2G are cross-section views illustrating successive steps ofan example of a method of manufacturing such a device.

FIG. 2A very schematically illustrates an initial structure whichcorresponds to a structure of the type obtained by the method of FIGS.1A to 1J, comprising an integrated control circuit stage 151 topped witha photodetection stage 201, itself topped with an emission stage 203.Photodetection stage 201 comprises a plurality of photosensitive diodes171 (not detailed in FIGS. 2A to 2G) individually controllable byintegrated circuit 151. The emission stage comprises a plurality of LEDs161 (not detailed in FIGS. 2A to 2G) individually controlled byintegrated circuit 151. In FIG. 2A, only the electric connection pads153 of integrated circuit 151, arranged on the upper surface side ofintegrated circuit 151, have been detailed.

FIG. 2B illustrates a step of bonding of the structure of FIG. 2A onto atemporary support substrate 210, for example, made of silicon. Thestructure of FIG. 2A is bonded to support substrate 210 by its surfaceopposite to integrated control circuit 151, that is, by its lowersurface in the orientation of FIG. 2B, corresponding to its uppersurface in the orientation of FIG. 2A.

FIG. 2C illustrates an optional step of thinning of the semiconductorsubstrate of integrated circuit 151, from its surface opposite to stages201 and 203. As an example, integrated circuit 151 is initially formedinside and on top of a substrate of SOI (“Semiconductor On Insulator”)type. The SOI substrate for example comprises a silicon support, coatedwith an insulating layer, itself coated with a single-crystal siliconlayer (not detailed in the drawings). The components, particularlytransistors, of integrated circuit 151, may be formed inside and on topof the single-crystal silicon layer of the SOI substrate. The thinningstep of FIG. 2C may comprise removing the support substrate of the SOIsubstrate, to only keep the single-crystal silicon layer and theinsulating layer of the SOI substrate.

As a variant, integrated circuit 151 is formed inside and on top of asolid silicon substrate, and the thinning step may then comprisedecreasing the substrate thickness, for example, by grinding, from itsupper substrate (in the orientation of FIG. 2C). An insulatingpassivation layer (not detailed in the drawing) may then be deposited onthe upper surface of the thinned substrate.

FIG. 2D illustrates a step of forming, on the upper surface side ofintegrated circuit 151, of metal connection pads 221 coupled toconnection pads 153 and/or to connection terminals of electroniccomponents, for example, MOS transistors, of integrated circuit 151, viaconductive vias not detailed in the drawing, crossing the semiconductorsubstrate of integrated circuit 151.

FIG. 2E illustrates a step of forming, from the upper surface ofintegrated circuit 151, of trenches 230 vertically crossing integratedcircuit 151, detection stage 201, and emission stage 203, and emergingonto the upper surface of temporary support substrate 210. Trenches 230laterally delimit a plurality of semiconductor chips 232 correspondingto the elementary chips of the pixel of the display device. Trenches 230may be formed by plasma etching, by sawing, or by any other adaptedcutting method.

FIGS. 2F and 2G illustrate a step of bonding of elementary chips 232onto the upper surface of a same transfer substrate 250 of the displaydevice. Transfer substrate 250 comprises, on its upper surface side, aplurality of metal connection pads 252, intended to be bonded andelectrically and mechanically connected to corresponding metalconnection pads 221 of the elementary chips 232.

The structure of FIG. 2E is turned upside down (FIG. 2F) to place themetal connection pads 221 of elementary chips 232 opposite correspondingmetal connection pads 252 of transfer substrate 250. Opposite pads 221and 252 are then bonded and electrically connected, for example, bydirect bonding, by welding, by means of microtubes, or by any otheradapted method.

Once bonded to transfer substrate 250, elementary chips 232 areseparated from temporary support substrate 210, and the latter isremoved (FIG. 2G). As an example, the separation of the chips isperformed by mechanical separation or by separation by means of laserbeam.

In the shown example, the pitch (center-to-center distance in frontview) of elementary chips 232 on transfer substrate 250 is a multiple ofthe pitch of elementary chips 232 on temporary support substrate 210.Thus, only part of elementary chips 232 (one out of two in the shownexample) are simultaneously transferred from temporary support substrate210 to transfer substrate 250. The other chips 232 remain attached totemporary transfer substrate 210 and may be subsequently onto anotherportion of transfer substrate 250 on onto another transfer substrate250.

Various embodiments and variants have been described. Those skilled inthe art will understand that certain features of these variousembodiments and variants may be combined, and other variants will occurto those skilled in the art. In particular, the described embodimentsare not limited to the examples of materials and/or of dimensionsmentioned in the present disclosure.

Further, in the example described in relation with FIGS. 1A to 1J, theanode regions 125 and the anode metallizations 127 of photosensitivediodes 171 are formed after the transfer of active photosensitive diodestack 103 onto integrated circuit 151. As a variant, not detailed in thedrawings, the anode regions 125 and the anode metallizations 127 ofphotosensitive diodes 171 may be formed before the transfer of activephotosensitive diode stack 103 onto active LED stack 113. In this case,the order of the layers of stack 103 is inverted with respect to theexample of FIG. 1A. The bonding of active photosensitive diode stack 103onto integrated circuit 151 then is a hybrid bonding requiring analignment of the anode metallizations 127 of the photosensitive diodeswith respect to the metal connection pads 153 of integrated circuit 151.However, an advantage is that the anneal for activating the dopants ofregions 125 can then be performed before the transfer of stack 103 ontointegrated circuit 151, which avoids any degradation of integrationcircuit 151 or of the bonding between stack 103 and integrated circuit151 during the anneal.

FIG. 3 schematically shows an example of a system comprising anoptoelectronic device 300 according to an embodiment.

Device 300 may be a device of monolithic microdisplay type, for example,formed by a method of the type described in relation with FIGS. 1A to1J.

As a variant, device 300 may be a device of larger dimensions, forexample formed by a method of the type described in relation with FIGS.2A to 2G.

Device 300 combines an image display function and an optical capturefunction, for example, to form an interactive display screen adapted toimplementing functions of face or shape recognition, of motiondetection, of identification, etc.

The system of FIG. 3 further comprises a light source 310. Source 310 isadapted to emitting a light radiation in the sensitivity range ofphotosensitive diodes 171 (not detailed in FIG. 3) of device 300. As anexample, source 310 is an infrared source, for example, a laser source.

In operation, source 310 illuminates a scene 320, an image of which isdesired to be acquired. The light emitted by source 310 is reflected byscene 320 and returned to device 300. The photosensitive diodes 171 ofdevice 300 then enable to acquire an image of scene 320 and/or tomeasure depth information relative to scene 320.

In the example of FIG. 3, light source 310 is a remote source, that is,it is distinct from device 300. The control of light source 310 and thecontrol of the detection pixels of device 300 are for examplesynchronized.

FIG. 4 is a cross-section view schematically and partially illustratinganother example of an optoelectronic device according to an embodiment.

In this example, the optoelectronic device integrates a distributedlight source emitting in the sensitivity range of photodiodes 171, forexample, an infrared source. This enables to do away with the remotesource 310 of the system of FIG. 3.

The device of FIG. 4 comprises elements common with the device of FIG.1J. These elements will not be detailed again hereafter, and only thedifference with respect to the device of FIG. 1J will be highlighted.

In the example of FIG. 4, two LEDs 161(a) and 161(b) of the device, forexample, identical or similar, have been shown. LEDs 161(a) and 161(b)are adapted to emitting light in the same wavelength range, for example,mainly blue light. The described embodiments are however not limited tothis specific example and it will be within the abilities of thoseskilled in the art to adapt the example of embodiment described inrelation with FIG. 4 to other emission colors of LEDs 161.

In this example, LED 161(a) is coated, on its upper surface side, with aphotoluminescent conversion element 181(a) adapted to converting thelight emitted by the LED into visible light at another wavelength, forexample, into red or green light in the case of a LED emitting bluelight.

As an example, in the case of LEDs emitting blue light, three types ofvisible light emission pixels adapted to respectively emitting red light(by means of a photoluminescent conversion element converting the bluelight emitted by the underlying LED into red light), green light (bymeans of a photoluminescent conversion element converting the blue lightemitted by the underlying LED into green light), and blue light (with noconversion element), may be provided.

LED 161(b) is coated, on its upper surface side, with a photoluminescentconversion element 181(b) adapted to converting the light emitted by theLED into a light radiation in the wavelength range detected by thephotosensitive diodes 171 of the device, for example, an infraredradiation.

Thus, LED 161(b) defines an emissive pixel PIR of a light sourceintegrated to the optoelectronic device, adapted to cooperating withphotosensitive diodes 171 and replacing the source 310 of the system ofFIG. 3.

As previously described, the device of FIG. 4 may be a device ofmonolithic microdisplay type, or a pixel of a device of largerdimensions.

The number and the repetition pitch of pixels PIR may be selectedaccording to the needs of the application. For example, the device maycomprise fewer pixels PIR than visible pixels (defined by LEDs 161(a))of a same emission color. Preferably, the final device (monolithicmicrodisplay or extended device) comprises a plurality of pixels PIRdistributed over the surface of the device.

The conversion elements 181(a), 181(b) topping LEDs 161(a), 161(b) arefor example formed based on quantum dots or based on perovskitematerials, preferably inorganic perovskite materials, preferablyepitaxial inorganic perovskite materials. The conversion elements basedon perovskite materials are for example deposited by pulsed laserdeposition (PLD).

FIG. 5 is a cross-section view schematically and partially illustratingan alternative embodiment of the device of FIG. 4.

The variant of FIG. 5 differs from the example of FIG. 4 in that itfurther comprises opaque walls 191, for example, made of resin,laterally separating the emissive pixels from one another and laterallyseparating emissive pixels from detection pixels. This particularlyenables to avoid for the light emitted by pixels PIR to directly reachphotosensitive diodes 171, without passing through the scene, an imageof which is desired to be acquired.

1. Optoelectronic device manufacturing method, comprising the steps of:a) arranging an active photosensitive diode stack on a first substrate;b) transferring the active photosensitive diode stack onto an integratedcontrol circuit previously formed inside and on top of a secondsemiconductor substrate, and then removing the first substrate; c)arranging an active light-emitting diode stack on a third substrate; andd) after steps b) and c), transferring the active light-emitting diodestack onto the active photosensitive diode stack, and then removing thethird substrate.
 2. Method according to claim 1, wherein the activephotosensitive diode stack comprises at least one inorganicsemiconductor layer, for example, made of a III-V material, and whereinthe active light-emitting diode stack comprises at least one inorganicsemiconductor layer, for example, made of a III-V material.
 3. Methodaccording to claim 1, wherein the active photosensitive diode stackcomprises first, second, and third semiconductor layers, the secondlayer being arranged between the first and third layers.
 4. Methodaccording to claim 3, comprising a step of P-type doping of localportions of the first layer, said portions defining anode regions ofphotosensitive diodes of the device.
 5. Method according to claim 4,wherein said step of P-type doping of the local portions of the firstlayer is implemented after step b) and before step d).
 6. Methodaccording to claim 4, wherein said step of P-type doping of the localportions of the first layer is implemented before step b).
 7. Methodaccording to claim 4, further comprising a step of forming of connectionmetallizations on top of and in contact with said local portions of thefirst layer.
 8. Method according to claim 1, wherein, at the end of stepb), the active photosensitive diode stack continuously extends over theentire surface of the integrated control circuit.
 9. Method according toclaim 1, wherein, at the end of step d), the active light-emitting diodestack continuously extends over the entire surface of the integratedcontrol circuit.
 10. Method according to claim 1, further comprising,after step b) and before step d), a step of forming of conductive viascrossing the active photosensitive diode stack.
 11. Method according toclaim 10, wherein the conductive vias are electrically connected tometal connection pads of the integrated circuit.
 12. Method according toclaim 1, further comprising, after step d), a step of local etching ofthe active light-emitting diode stack to form in the activelight-emitting diode stack a plurality of tiles, each defining alight-emitting diode.
 13. Method according to claim 12, comprising theforming of color conversion elements, above at least some of thelight-emitting diodes.
 14. Method according to claim 13, wherein atleast one of said light-emitting diodes is topped with aphotoluminescent conversion element adapted to converting the lightemitted by the light-emitting diode into a visible wavelength and atleast another one of said light-emitting diodes is topped with aphotoluminescent conversion element adapted to converting the lightemitted by the light-emitting diode into a light radiation in thewavelength range of sensitivity of the active photosensitive diodestack, preferably an infrared radiation.
 15. Method according to claim14, wherein at least one of said light-emitting diodes is not toppedwith a photoluminescent conversion element.
 16. Method according toclaim 13, wherein said photoluminescent conversion elements, are formedbased on quantum dots or on perovskite materials.
 17. Method accordingto claim 1, comprising, after step d), a step of bonding of a temporarysupport substrate on the side of the active light-emitting diode stackopposite to the integrated circuit, followed by a step of cutting of theassembly comprising the integrated circuit, the active photosensitivediode stack, and the active light-emitting diode stack into a pluralityof elementary chips.
 18. Method according to claim 13, furthercomprising a step of transfer and of bonding of said elementary chipsonto a transfer substrate of the device, followed by a step of removalof the temporary support substrate.
 19. Optoelectronic device comprisinga transfer substrate and a plurality of elementary chips bonded andelectrically connected to the transfer substrate, each elementary chipcomprising a stack comprising, in the order from the upper surface ofthe transfer substrate, an integrated control circuit formed inside andon top of a semiconductor substrate, a photodetection stage comprisingat least one photosensitive diode, and an emission stage comprising atleast one light-emitting diode.
 20. Device according to claim 15,wherein, in each elementary chip, the photodetection stage is arrangedbetween the integrated control circuit and the emission stage, andwherein said at least one photosensitive diode has a semiconductor anodelayer arranged on the side of the emission stage and a semiconductorcathode layer arranged on the side of the integrated control circuit.21. System comprising an optoelectronic device formed by a methodaccording to claim 1, and a light source adapted to emitting a lightradiation in the wavelength range of sensitivity of the activephotosensitive diode stack, preferably an infrared radiation.
 22. Systemaccording to claim 21, wherein the light source is a remote source. 23.System according to claim 21, wherein the light source is integrated tothe optoelectronic device and comprises at least one light-emittingdiode formed in the active light-emitting diode stack.